A wide variety of keyed locks or locking mechanisms exist for preventing unauthorized or unwanted entry and/or use of various items and devices including without limitation vehicles, houses, drawers, doors, and the like. While conventional keyed locks and locking mechanisms are generally effective in preventing such unwanted entry and/or use, certain tools and methods have been devised to defeat or overcome the effectiveness of keyed locks in order to forcefully gain entry to and/or use of the locked item.
One well-known manner of overcoming a lock is to pick the lock. Picking a lock requires a great deal of knowledge about the internal workings of the particular lock being picked, and is often relatively time consuming. In addition, locks are continually being improved to make the process of picking certain types of locks extremely difficult, if not altogether impossible. Due to the inherent challenges of picking a lock, certain groups having primarily malicious intentions (most notably car thieves) have devised other commonly used methods for overcoming a lock. By inserting a rigid item (such as a screwdriver) into the lock instead of the appropriate key, and subsequently applying a sufficient torque to that item, many locks can be overcome by force. Such locks typically fail in one of two manners when forced as just described. In a first failure mode, the internal components of the lock (e.g. the lock tumblers, the lock cylinder, and the like) are broken such that the lock cylinder can be rotated with respect to the lock housing. Generally, rotation of the lock cylinder is all that is required to defeat many locks. In a second failure mode, the internal lock components remain intact while the lock housing itself breaks free of the structural item to which it is secured (e.g. a vehicle steering column or vehicle door). Oftentimes, dislodging the lock housing in this manner and rotating the entire lock assembly has the same effect as rotating the lock cylinder with respect to the housing, resulting in the lock being defeated.
In order to prevent the defeat of a lock by forcefully rotating the lock as just described, some lock designs employ strengthened lock components and strengthened connections between the lock and the object to which the lock is secured. However, these design changes have been largely unsuccessful because the resulting locks are still subject to damage by attempts to overpower the lock, can often be overcome with even greater force, and are often excessively robust and expensive to manufacture and install. Furthermore, strengthening of the lock components can require a subsequent strengthening of the lock connection, which can then require additional strengthening of other lock components, resulting in a costly and on-going cycle of lock re-design.
Other attempts to protect keyed locks and locking mechanisms from being overpowered include the development of freewheeling locks. Freewheeling locks are constructed such that rotation of the lock cylinder with substantially any item other than the correct key inserted causes the lock cylinder to disengage from those lock components needed to unlock the lock (e.g., a lock drive mechanism). In this way, forced rotation of the lock cylinder does not result in unlocking or overcoming the lock.
In an effort to improve upon known locks, some embodiments of the present invention provide a locking mechanism including a housing defining a cavity and a central axis and having a receiving end, a retaining end, and a first cam surface that is adjacent to the receiving end, and a sleeve received at least partially within the cavity and having a second cam surface engageable with the first cam surface of the housing, and a clutch surface. In such embodiments, a lock cylinder is received at least partially within the sleeve and has a locked configuration and an unlocked configuration. The lock cylinder and the sleeve are coupled for rotation together when the lock cylinder is in the locked configuration.
Some embodiments of the present invention have a clutch member that is received at least partially within a housing cavity and is movable therein. The clutch member can be engaged with the lock cylinder for joint rotation when the lock cylinder is rotated in the unlocked configuration. When the lock cylinder is rotated in the locked configuration, the clutch member moves within the cavity and disengages the lock cylinder. An actuator is coupled to the clutch member such that the actuator rotates with the clutch member, and the actuator and the clutch member are axially movable with respect to each other.
In addition, some embodiments of the present invention provide a lock assembly having a housing that at least partially defines a cavity and has a central axis, an actuator rotatably coupled to the housing and substantially axially fixed with respect to the housing, and a lock cylinder received at least partially within the cavity, having a locked configuration and an unlocked configuration, and rotatable with respect to the housing in both the locked and unlocked configurations. A clutch selectively couples the lock cylinder and the actuator for rotation together depending upon the configuration of the lock cylinder when the lock cylinder is rotated.